The longer the chain, the greater the strain: Evidence from multiple biological levels in mussels exposed to PFAS

Résumé fourni par la source

Long-chain per- and polyfluoroalkyl substances (PFAS) are persistent, bioaccumulative pollutants posing risks to marine life. This study quantified biochemical, physiological, and histopathological effects of four long-chain PFAS (PFUnDA, PFDoA, PFTriDA, PFTeDA) on the mussel Mytilus galloprovincialis. The Integrated Biomarker Response (IBR) index was used to assess the overall organismal stress. Longer-chain PFAS (PFTriDA, PFTeDA) triggered metabolic activation, increasing respiration and electron transport system activity, with protein and lipid accumulation and carbohydrate depletion. Antioxidant defenses were modulated in a compound-specific manner, and increased lipid peroxidation in several treatments indicated that these responses were not always sufficient to prevent oxidative damage. Biotransformation-related enzyme responses were also compound-specific, suggesting differential activation of detoxification pathways among PFAS treatments. Acetylcholinesterase inhibition suggested potential functional neurotoxicity. Histopathological index, especially in gills and digestive gland, showed higher values under PFTriDA and PFTeDA exposures, corroborated biochemical findings, mainly characterized by digestive tubule atrophy, brown cell aggregates in primary tubule epithelia, fibrous tissue formation in connective areas, and enlarged central vessels in gills. Overall, PFAS toxicity was chain length-dependent, with PFTriDA and PFTeDA eliciting the strongest oxidative, metabolic, and neurotoxic effects. These findings provide an integrated description of sublethal biological responses to selected long-chain perfluorocarboxylic acids in bivalves and support further investigation of chain-length-related effects using molecular and pathway-specific approaches.

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